Not end of IS fight, defence chief warns

Islamic State is nearing defeat in Iraq and Syria but the self-proclaimed caliphate is fighting to establish a foothold in Afghanistan, a Senate committee has been told.

This month marks three years since the RAAF began flying the first of 4100 sorties against IS in Iraq, a mission later expanded to cover Syria.

"The terrorists are on the back foot but it's not the end of the fight," defence force vice-chief Ray Griggs warned senators in Canberra on Wednesday as he provided an update of Middle East operations.

IS had lost 83 per cent of its territory including its de-facto capitals Mosul in Iraq and Raqqa in Syria.

"What we are seeing is Daesh (IS) in Iraq in full-scale retreat," Vice-Admiral Griggs said.

Much of the remaining IS pockets around the Euphrates River Valley areas were over difficult terrain.

Admiral Griggs said IS was also fighting for a foothold in Khorasan province in Afghanistan, although the Taliban remained the biggest threat there.

In May Australia made a modest boost of 30 to its mission, bringing total troops in Afghanistan to 300.

Australia has six Super Hornets conducting sorties across Iraq and Syria, along with an air-to-air refuelling tanker and Wedgetail early warning and control aircraft.

The aircraft were still flying missions but not dropping weapons at the moment.

Australia's total contribution to the fight against IS in Iraq and Syria is 780 personnel for air operations, training and mentoring Iraqi soldiers and police, and carrying out special operations.